Hepatic stearoyl-CoA desaturase (SCD)-1 activity and diacylglycerol but not ceramide concentrations are increased in the nonalcoholic human fatty liver.
OBJECTIVE
To determine whether 1) hepatic ceramide and diacylglycerol concentrations, 2) SCD1 activity, and 3) hepatic lipogenic index are increased in the human nonalcoholic fatty liver.


METHODS
We studied 16 subjects with (n = 8) and without (n = 8) histologically determined nonalcoholic fatty liver (NAFL(+) and NAFL(-)) matched for age, sex, and BMI. Hepatic concentrations of lipids and fatty acids were quantitated using ultra-performance liquid chromatography coupled to mass spectrometry and gas chromatography.


RESULTS
The absolute (nmol/mg) hepatic concentrations of diacylglycerols but not ceramides were increased in the NAFL(+) group compared with the NAFL(-) group. The livers of the NAFL(+) group contained proportionally less long-chain polyunsaturated fatty acids as compared with the NAFL(-) group. Liver fat percent was positively related to hepatic stearoyl-CoA desaturase 1 (SCD1) activity index (r = 0.70, P = 0.003) and the hepatic lipogenic index (r = 0.54, P = 0.030). Hepatic SCD1 activity index was positively related to the concentrations of diacylglycerols (r = 0.71, P = 0.002) but not ceramides (r = 0.07, NS).


CONCLUSIONS
We conclude that diacylglycerols but not ceramides are increased in NAFL. The human fatty liver is also characterized by depletion of long polyunsaturated fatty acids in the liver and increases in hepatic SCD1 and lipogenic activities.
Kotronen
Anna
A
Department of Medicine, Division of Diabetes, Helsinki, Finland. anna.kotronen@helsinki.fi
Seppänen-Laakso
Tuulikki
T
Westerbacka
Jukka
J
Kiviluoto
Tuula
T
Arola
Johanna
J
Ruskeepää
Anna-Liisa
AL
Oresic
Matej
M
Yki-Järvinen
Hannele
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D002518:Ceramides / Q000378:metabolism*; D002853:Chromatography, Liquid; D004075:Diglycerides / Q000378:metabolism*; D005234:Fatty Liver / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D013230:Stearoyl-CoA Desaturase / Q000378:metabolism*; D055815:Young Adult
D002518:Ceramides; D004075:Diglycerides; D013230:Stearoyl-CoA Desaturase